胸部DR摄影中管电压对影像质量和辐射剂量影响的模体研究

目的 研究胸部数字X射线摄影(DR)中,不同管电压对影像质量以及受检者辐射剂量的影响。方法 管电压在80~130 kV范围内间隔10 kV变化,每种管电压设置下自动曝光控制(AEC)范围在-4~4对成人胸部模体进行曝光。测量模体表面的皮肤入射剂量,计算相对噪声值和对比度噪声比(CNR),并估算每次曝光时受检者的有效剂量。结果 皮肤入射剂量为(0.062 9±0.027 4)mGy,有效剂量为(0.012 7±0.004 5)mSv,有效剂量随着皮肤入射剂量的增加而呈线性增加,两者呈正相关关系(r=0.912,P<0.01)。随着有效剂量的增加,相同管电压下,相对噪声与有效剂量呈负相关关系(r=-0.967、-0.969、-0.968、-0.969、-0.968、-0.970, P<0.01);CNR与有效剂量呈正相关关系(r=0.987、0.987、0.986、0.987、0.988、0.989,P<0.01)。AEC不变时,随着kV值增加,皮肤入射剂量和有效剂量均降低,最大可降低50%和20%;相对噪声值降低,最大可降低23%;CNR增加,最大可增加8%。结论 胸部DR摄影中,在满足影像质量要求的前提下,高kV值可有效降低受检者辐射剂量。

A phantom study of the influence of tube voltage on image quality and radiation dose in DR chest radiography

Objective To investigate the influence of tube voltage on image quality and radiation dosage to subjects in chest digital radiography (DR). Methods An adult chest phantom was exposed in the range of 80-130 kV with the interval of 10 kV and the automatic exposure control (AEC) setting was selected from -4 to 4. The entrance skin dose (ESD) of the phantom was measured, and the relative noise, contrast-to-noise ratio (CNR) and the effective dose of each exposure was calculated. Results The ESD was (0.062 9±0.027 4) mGy, and the effective dose was (0.012 7±0.004 5) mSv. The effective dose increased linearly with the ESD, and there was a positive correlation (r=0.912, P<0.01). When the tube voltage was held constant, the relative noise decreased as the effective dose increased (r=-0.967, -0.969, -0.968, -0.969, -0.968, -0.970, P<0.01). The CNR increased with the effective dose increasing under the same tube voltage (r=0.987, 0.987, 0.986, 0.987, 0.988, 0.989, P<0.01). The ESD and effective dose decreased as the kV values increased under the same AEC, and the degree of decrease could be up to 50% and 20%. The relative noise decreased as the kV values increased under the same AEC, and the degree of decrease could be up to 23%. The CNR values increased up to 8%. Conclusions The use of higher kVp in chest digital radiography can reduce the radiation dose to some extent.